Protecting device for electric detonators



Nov. 23 1926. 1 ,607,818

A. DJIDICS PFEOTECTING DEVICE FOR ELECTRIC DETONATORS Filed NOV. 20, 1925 6 q I I avwemto'o Alexander 0'65 Patented Nov. 23, 1926.

. N i T ill arll ALEXANDER DJIDICS, G1? TAlvLEiQUA, EENNSYLVANEA, ASSIGNOR T0 ATLAS PGWDEB COMPANY, 033 VIILIVTINC-TGN, DELAVJARE, A CORPORATION 0F DELAW'ARE.

PROTECTING DEVICE FOR ELECTRIC DE'IOHATURS.

Application filed November 20, 1925.

This invention relates to a protecting device for electric detonators and is intended to be applied to the lead-in wires of such detonators and to serve, while in position, to establish a short circuit between the two lead-in wires, so that any stray currents imposed upon the lead-in wires, outwardly of the point of application of said device, may not find their way to the detonator and prematurely explode the same and so that the difference in potential between the lead wires can be created, inwardly of the point of application of the device, under the influence of accidental or stray currents.

I am aware of the fact that it has been proposed to short circuit the main firing cable leading from the blasting machine. However, that method is of utility only at the time of use. An important object of the present invention is to provide a structure which will be operative with respect to the individual detonators, at all times between the time of manufacture of the detonator and until the same is actually exploded on the job, the structure being of particular utility during the time that the detonator is being transported and while it is being handled about the work preliminary to the actual connection of its lead wires to the main firing cable.

The present application is directed to the protection of a specific form of short circuiting shunt and method of applying the same to the lead-in wires of the individual blasting caps, with its inner end abutting and resting firmly against the terminal end of the usual insulation of the detonators.

In the accompanying drawing:

Fig. 1 is a side elevation of an electric detonator with the shunt of the present invention applied thereto, and

Fig. 2 is a view of the shunt upon an enlarged scale.

Referring to the drawing, 5 designates the conventional electric detonator and G and 7 designate the usual lead-in wires of said detonator.

In the ordinary use of the detonator, the flow of current of sutficient strength past an igniting element 8, which connects the inner ends of the wires 6 and 7 explodes the detonator. The lead-in wires are insulated, as indicated at 9 and 10, for some dis tance from the detonator, and the ends of the lead-in wires are left bare beyond the Serial No. 70,282.

point Where the insulation terminates, to adapt them for ready application to the firing cable leading from a blasting machine.

In carrying out the present invention, 1 apply a non-metallic, non-inflammable bind or 11 to the bared portions of the wires 6 and 7, directly at the point where the insulation terminates. The material employed is preferably asbestos cord and when it is wrapped around the wires, the wires are bound into electrical contact with each other, to thereby create a short circuit at the point of application of said cord or binder. Since the lead wires are protected from the point of application of the binder, inwardly to the detonator, by the insulating material thereon, it follows that the contact of the lead wires with elements carrying stray electric currents, cannot, by any possibility, explode the detonator. The results of exhaustive tests have shown that if the wires are joined by means of a non-inflammable cord or binding strip, the cap cannot be fired by the electric current and that the efiicienoy of the joint is not afiiected in any way by the heat produced when a heavy current passes through the wires. The invention is not limited with respect to any particular way of securing the ends of the cord since they may be tied if necessary. However, I have found a very simple and inexpensive way of securing these cords, to reside in engaging their terminal ends between the lead wires, as illustrated in the drawing. These terminal ends are thus frictionally held to an extent to hold them securely in place. This arrangement facilitates the ready removal of the binder when the time of use of the detonator arrives. It is not to be understood that the device is of utility only when actually touching the termination of the insulation. It will give a very appreciable measure of protection even when spaced somewhat from the insulation because the influences which might bring about such difference in potential between the lead wires as to explode the detonator, are not those sought to be created by an intelligent human agency but only those which might accidently occur. Stray currents of such low M. F. as to escape ordinary notice constitute a marked source of danger and are rendered absolutely harmless by this invention.

It is to be understood that the invention is not limited to the precise arrangement set forth but that it includes Within its pun View Whatever changes fairly come Within either the terms or the spirit of the appended claims.

Having described my invention, What I claim is: I

1. The. combination with a detonator and its bifilar lead in Wires, of a non-metallic, non-infiammable cord Wound about the same close to the termination of the insulation upon said wires and having its terminal ends retained by being engaged beteen said Wires.

2. A binder of the character described in claim 1, consisting of a piece of asbestos cord.

3. The combination with a detonator and its bifilar lead-in Wires, of a Winding of asbestos cord directly at the termination of the insulation upon said Wires.

4. A structure as recited in claim 3, Wherein the terminal ends of the asbestos cord are engaged between the lead-in wires, to be re tained thereby.

5. The combination with a detonator and its bifilar lead-in wires of an asbestos binder upon the lead-in Wires close to the. point of termination of the insulation thereon.

ALEXANDER DJIDTCS. 

